With the threat of biological warfare being much more probable in light of recent attacks on the United States, a rapid and sensitive means to detect bio-agents is desirable if treatments for infection are to be administered in time to prevent loss of life. Conventionally, it may take several days to verify the presence of, for example, anthrax and such tests generally only test for the presence of a single agent.
Micro-array technology holds the promise of increased diversity, speed and sensitivity in the identification of several bioactive agents. Devices that deliver pre-synthesized oligonucleotides in small, well-defined spots onto solid substrates using ink-jet delivery may be employed to create DNA arrays that may be used to test for a large number of analytes on a chip the size of a microscope slide; however, there are current limitations to conventional detection sensitivities. Generally, DNA micro-arrays require sample volumes on the order of about 10–50 μL and (for most practical platforms) the detection sensitivities only reach about 100 fM or about 0.6E9 molecules. Some magnetoresistive techniques currently in development at the Naval Research Laboratory are anticipated to improve conventional detection limits by at least three orders of magnitude; however, this is still far from the regime of single molecule detection. Accordingly, despite the efforts of the prior art, one problem warranting resolution is the single molecule detection of a variety of bioactive agents using DNA hybridization techniques.